ONS Connect - February 2008 - (Page 25) NEwTrEaTmENTS,NEwhOpE Virus Related to Smallpox May Help Fight Cancer [By Deborah McBride, RN, MSN, CPON ®, Contributing Editor] modified relative of the smallpox virus has shown promise in fight ing liver cancer, according to two recent research reports. Scientists have been trying to ge netically engineer viruses to infect and destroy cancer cells for more than 10 years but have had limited success. Recent clinical trials offered hope that the approach might work, but experts say the specifically designed viruses do not replicate fast enough in tumors to impact tumor growth. Researchers overcame that by using genetically engi neered vaccinia, a relative of the small pox virus, which spreads more easily in cancer tumors. In the first study, the virus was test ed on 13 patients with advanced liver cancer (Park et al., 2007). The virus A appeared to reduce the size of the tu mors in 10 of the patients. Five of the patients enrolled in the trial experi enced a greater than 50% reduction in the size of their tumors over the year long trial. The tumortargeting vaccinia virus known as JX594 was injected directly into subjects’ tumors every three weeks. The chemical that the virus secretes, granulocyte macrophage–colonystim ulating factor, is a protein that stimu lates the production of white blood cells, causing patients’ immune systems to attack the cancer. According to the researchers, the pa tients all had a poor prognosis with a life expectancy of three to four months. After treatment with the JX594 virus, seven of the participants survived for more than eight months, and three were still alive more than 15 months later. The only notable side effect was tempo rary flulike symptoms from the injec tions. The second study found that another modified vaccinia virus called JX963 reduced liver tumor growth in rabbits (Thorne et al., 2007). More than 80% of the animals treated with JX963 showed a greater than 50% reduction in tumor size. In animals that did not receive the virus, tumors grew four times larger and new lung tumors ap peared. The cancer might be knocked out altogether by higher doses of the virus or combinations of it and other medications. Based on the positive results from the preliminary clinical trials and ani mal experiments, phase II trials will be conducted to see whether the virus can help treat other types of tumors, such as head and neck cancers. Trials are expected to begin in early 2008. ✱ Park, B., Hwang, T., Kim, S., et al. (2007, Octo ber). A phase I–II clinical trial with JX-594, a targeted and GM-CSF-armed oncolytic poxvirus, by the intratumoral injection in patients with liver tumors [Poster A156]. Presented at the AACR NCIEOTRC International Conference: Molecu lar Targets and Cancer Therapeutics, San Fran cisco, CA. Thorne, S.H., Hwang, T.H., O’Gorman, W.E., Bartlett, D.L., Sei, S., Kanji, F., et al. (2007). Rational strain selection and engineering cre ates a broadspectrum, systemically effective oncolytic poxvirus, JX963. Journal of Clinical Investigation, 117(11), 3350–3358. Contributing Editor Deborah McBride, RN, MSN, CPON ®, is a nurse at the Kaiser Permanente Oakland Medical Center and a faculty member at Samuel Merritt College in Oakland, CA. February 2008 ONS CONNECT 25
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